Current Carrying Conductor

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Mike01

Senior Member
Location
MidWest
Why is a neutral for a 120V branch circuit not considered a current carrying conductor? Where when used as part of a multi-wire branch circuit it is?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
The neutral on a multiwire branch circuit only carries the unbalanced load. For instance on a single phase panel with "A" equal to 10 and "B" equal to 15 amps the neutral only carries the difference between A and B or 5 amps. There can never be a time when there are more than 2 CCC in this setup.
 

jumper

Senior Member
Rob/Infinity wrote this, hope it helps:

Here's some examples of when to count the neutral as a CCC:

208Y/120 volt system-different circuit types:

A)- 2 wire circuit w/ 1 ungrounded, 1 neutral = 2 CCC's
B)- 3 wire circuit w/ 2 ungrounded, 1 neutral = 3 CCC's
C)- 4 wire circuit w/ 3 ungrounded, 1 neutral = 3 CCC's*

Notes:
A)- A normal 2 wire circuit has equal current flowing in each of the circuit conductors so they both count as CCC's.
B)- In this circuit the neutral current will be nearly equal to the current in the ungrounded conductors so the neutral counts as a CCC
C)- In this circuit the neutral will only carry the imbalance of the current between the three ungrounded conductors so it is not counted as a CCC, with one exception, *if the current is more than 50% nonlinear then the neutral would count as a CCC.

120/240 volt system-different circuit types:

D)- 2 wire circuit w/ 1 ungrounded, 1 neutral = 2 CCC's
E)- 3 wire circuit w/ 2 ungrounded, 1 neutral = 2 CCC's

Notes:
D)- A normal 2 wire circuit has equal current flowing in each of the circuit conductors so they both count as CCC's.
E)- In this circuit the neutral will only carry the imbalance between the two ungrounded conductors so the neutral is not counted as a CCC.
Rob
 

cdslotz

Senior Member
When you have specs that require no shared neutrals, pulling home runs get challenging, and costly with derating issues.
A lot more home run conduits are needed.
 
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